You can change that in Settings → Privacy and security → Invitations → Select My contacts

>You can change that in Settings → Privacy and security → Invitations → Select My contacts

Bizarre that that's not the default and that it's actually an option at all.

Not bizarre at all. How else would you invite people (study group, work, etc). Especially thinking 10 years back.

This is a sensible default for most people. If it is no more, then settings can be changed.

Wouldn't you first add those people as a contact?

If you use Telegram in a 100% private setting (only friends and family and private groups) you won't be invited anywhere else either.

When your name is out there in public channels things change. Just like with an email address

driving interaction count > your peace